Moles are insectivores and tunnel through yards looking for earthworms, grubs, and beetles, they create subsurface tunnels just below the grass roots. This air pocket deprives the roots of moisture and kills the plants.

Voles are vegetarians and like to eat the grass shoots above ground. These trails on on the surface an many times are void of vegetation. In the spring time after snow melt you may see evidence of this including grass clipping piles that voles used for nests.